1. Field of Inventive concepts
Present Inventive concepts relate to nonvolatile memory devices.
2. Description of Related Art
Nonvolatile memory devices using resistance materials include Phase Change Random Access Memories (PRAMs), Resistive RAMs (RRAMs), and Magnetic RAMs (MRAMs). Unlike Dynamic RAMs (DRAMs) or flash memories that store data as charge, nonvolatile memory devices using resistance materials use a phase-changeable material such as a chalcogenide alloy (RRAM), a variable resistance material (RRAM), and/or a Magnetic Tunnel Junction (MJT) thin films having a variable magnetization state (MRAM).
As one example of a nonvolatile memory device using a variable resistance material, the PRAM will be described in some additional detail. The phase-change material used in conventional PRAMs goes into a crystalline state or an amorphous state due to a change in temperature by cooling followed by heating. Since the resistance of a phase-change material in the more crystalline state is relatively low and the resistance of a more amorphous phase-change material is relatively high, the crystalline state is referred to as set data and the amorphous state is referred to as reset data.
Meanwhile, as the memory capacity of a nonvolatile memory device increases, it may be necessary to use an error correction circuit to correct an error of a failed memory cell. The error correction circuit may be based on, for example, a method using a redundancy memory cell and an ECC (Error Correction Code) method.
Here, the ECC method employs an ECC encoder and an ECC decoder, which may be relatively large in size. Therefore, it may be difficult to reduce a chip size of a nonvolatile memory device using the ECC method.